What are the best methods to prevent spam email subscriptions and subscription bombing?
Summary
What email marketers say13Marketer opinions
Email marketer from Email Geeks warns that double opt-in (DOI) can become part of a spam bomb if other preventative measures aren't in place.
Email marketer from StackOverflow suggests implementing strict email address validation to filter out invalid or suspicious email addresses during the subscription process.
Email marketer from Neil Patel shares that implementing a double opt-in process ensures that only users who confirm their email address are added to the list, reducing the chances of spam subscriptions.
Email marketer from OptinMonster explains that you can block specific email addresses or domains that are repeatedly used for spam subscriptions to prevent them from joining your list.
Email marketer from HubSpot shares that using a confirmed opt-in (COI) process helps to ensure that subscribers are genuinely interested in receiving emails, preventing bots and unauthorized subscriptions.
Email marketer from MarketingOverCoffee suggests blocking signups from disposable email address services to prevent temporary or fake email addresses from being added to your list.
Email marketer from Email Geeks shares that implementing honeypots stopped bots from subscribing. They chose honeypots over reCAPTCHA due to SEO considerations.
Email marketer from EmailToolTester suggests implementing CAPTCHA on signup forms to distinguish between human users and bots, preventing automated spam subscriptions.
Email marketer from Litmus suggests monitoring where your signups are coming from and identifying patterns, potentially blocking traffic from suspicious sources if you notice an influx of bad signups.
Email marketer from Mailchimp explains the importance of regularly cleaning your email list by removing inactive or unengaged subscribers, which helps maintain deliverability and reduces spam complaints.
Email marketer from Email Geeks advises against blocking email addresses containing '+', as many users legitimately use them for tagging. Instead, they suggest using a honeypot field and captcha.
Email marketer from Email Geeks suggests implementing captcha, honeypot fields, anti-fraud systems, blocking duplicate signups based on stripped local parts of the address, and rate-limiting signups from one IP.
Email marketer from Reddit explains that a honeypot is a hidden field in your subscription form. Bots will fill it out, but legitimate subscribers won't see it. If the honeypot is filled, you know it's a bot.
What the experts say5Expert opinions
Expert from Email Geeks suggests captcha and confirmed opt-in (COI) as strong measures against subscription bombing.
Expert from Word to the Wise stresses the importance of confirmed opt-in (COI) to ensure subscribers genuinely want to receive emails, filtering out bot signups.
Expert from Spam Resource explains that methods to prevent email address harvesting, include masking email addresses on websites, which makes it harder for bots to find and collect them.
Expert from Word to the Wise advises that removing inactive subscribers helps maintain deliverability and reduces the likelihood of being flagged as spam, as engagement is a key factor for mailbox providers.
Expert from Email Geeks suggests that the user is likely experiencing subscription bombing and advises checking signup metadata like IP and user-agent.
What the documentation says4Technical articles
Documentation from OWASP explains that honeypots can be created as decoy form fields that are invisible to users but will be filled out by bots, thereby identifying them as malicious.
Documentation from Google Developers explains that implementing reCAPTCHA v3 helps to verify if an interaction is legitimate without user friction, using a score-based system to detect bots.
Documentation from Cloudflare explains that rate limiting can prevent subscription bombing by restricting the number of sign-up attempts from a single IP address within a defined time frame.
Documentation from StopForumSpam explains that they maintain a database of IP addresses and email addresses known for spam activity, which can be used to block malicious sign-ups.